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Photosynthesis of vitamin D in the skin: effect of environmental and life-style variables.
Fed Proc. 1987 Apr; 46(5):1876-82.FP

Abstract

Exposure to sunlight continues to play a major role in providing adequate vitamin D nutrition for most of the population of the world, including those who live in countries that practice fortification of dairy, margarine, and cereal products with vitamin D. During exposure to sunlight, the high-energy UV photons (290-315 nm) penetrate the epidermis and photolyze 7-dehydrocholesterol (provitamin D3) to previtamin D3. Once formed, previtamin D3 undergoes a thermally induced isomerization to vitamin D3 that takes 2-3 days to reach completion. Melanin effectively competes with provitamin D3 for the UV radiation that enters the epidermis and limits its photolysis to previtamin D3. However, this is not the major factor that prevents excess production of vitamin D in the skin of people who are constantly exposed to sunlight. During the initial exposure to sunlight, provitamin D3 is efficiently converted to previtamin D3. However, because previtamin D3 is photolabile, continued exposure to sunlight causes the isomerization of previtamin D3, principally to lumisterol. Thus, no more than 10-20% of the initial provitamin D3 concentrations ultimately end up as previtamin D3. Aging, sunscreens, seasonal changes, time of day, and latitude also significantly affect the cutaneous production of this vitamin-hormone.

Authors

No affiliation info available

Pub Type(s)

Historical Article
Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

3030826

Citation

Holick, M F.. "Photosynthesis of Vitamin D in the Skin: Effect of Environmental and Life-style Variables." Federation Proceedings, vol. 46, no. 5, 1987, pp. 1876-82.
Holick MF. Photosynthesis of vitamin D in the skin: effect of environmental and life-style variables. Fed Proc. 1987;46(5):1876-82.
Holick, M. F. (1987). Photosynthesis of vitamin D in the skin: effect of environmental and life-style variables. Federation Proceedings, 46(5), 1876-82.
Holick MF. Photosynthesis of Vitamin D in the Skin: Effect of Environmental and Life-style Variables. Fed Proc. 1987;46(5):1876-82. PubMed PMID: 3030826.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Photosynthesis of vitamin D in the skin: effect of environmental and life-style variables. A1 - Holick,M F, PY - 1987/4/1/pubmed PY - 1987/4/1/medline PY - 1987/4/1/entrez SP - 1876 EP - 82 JF - Federation proceedings JO - Fed Proc VL - 46 IS - 5 N2 - Exposure to sunlight continues to play a major role in providing adequate vitamin D nutrition for most of the population of the world, including those who live in countries that practice fortification of dairy, margarine, and cereal products with vitamin D. During exposure to sunlight, the high-energy UV photons (290-315 nm) penetrate the epidermis and photolyze 7-dehydrocholesterol (provitamin D3) to previtamin D3. Once formed, previtamin D3 undergoes a thermally induced isomerization to vitamin D3 that takes 2-3 days to reach completion. Melanin effectively competes with provitamin D3 for the UV radiation that enters the epidermis and limits its photolysis to previtamin D3. However, this is not the major factor that prevents excess production of vitamin D in the skin of people who are constantly exposed to sunlight. During the initial exposure to sunlight, provitamin D3 is efficiently converted to previtamin D3. However, because previtamin D3 is photolabile, continued exposure to sunlight causes the isomerization of previtamin D3, principally to lumisterol. Thus, no more than 10-20% of the initial provitamin D3 concentrations ultimately end up as previtamin D3. Aging, sunscreens, seasonal changes, time of day, and latitude also significantly affect the cutaneous production of this vitamin-hormone. SN - 0014-9446 UR - https://www.unboundmedicine.com/medline/citation/3030826/Photosynthesis_of_vitamin_D_in_the_skin:_effect_of_environmental_and_life_style_variables_ L2 - https://medlineplus.gov/vitamind.html DB - PRIME DP - Unbound Medicine ER -